While many different types of rotary hole saws or hole cutters have been suggested in the past, none of them has been entirely satisfactory for cutting holes in ceramic tile, particularly in ceramic tiles which have hard glazed surfaces, such as those used for bath tub enclosures and the like. So-called diamond core drills and carbide grit hole saws have been recommended for use on ceramic tile.
While a diamond core drill will, of course, cut through a ceramic tile, experience has shown that a water spray must be employed to cool the drill while it is cutting or the diamonds will be lost. Not only does this necessitate auxiliary equipment to supply the cooling water, but the tiles become saturated with water which tends to make them incompatible with adhesives used to hold the tile in place.
Hole saws with carbide grit bonded to their teeth also will cut through ceramic tile. However, actual tests have shown that such a saw will only cut a few holes before much of the carbide grit is lost and, of course, the grit cannot be replaced nor can the saw be re-sharpened.
It is therefore the principal object of the instant invention to provide a hole cutter for hard materials, such as ceramic tile, which is so designed as to minimize the chipping of the hard material and particularly the glazed surfaces of ceramic tile when a hole is being cut.
A further object is to provide a hole cutter having cutting blades which have carbide tips thereby providing a long life and which readily can be removed and replaced when necessary.
Another object of the instant invention is to provide a rotary hole cutter for ceramic tile which is so designed as to minimize "chattering" and the resulting irregularities in the hole edges.
It is yet another object of the instant invention to provide a hole cutter for ceramic tile wherein relative rotation between the pivot drill and the cutter body is eliminated and where the tendency of the cutters mounted on the body to flare outwardly is minimized.